What is a tax? Is it a “burden”? Or a “civilization surcharge”? And which would you rather pay? Would you prefer to vote for someone who has a “heart of gold” or a “heart of blackness”? Is crime a “beast” that is “ravaging” cities or a “virus” that needs to be controlled?

Metaphors allow us to represent and understand things in an instant, without having to engage in too much deliberation, simply by subsuming something new under something we already know. We know what a burden is, so if a politician cleverly talk about a “tax burden”, then we instantly understand the implications of that—and may vote for the cut in taxes advocated by that politician.

The task force thus highlighted two contrasting metaphors for the police: that of guardian and that of a warrior, where the latter highlights the similarity between the police and the military and the former highlights the role of the police in helping their community.

A recent article in the Psychonomic Bulletin & Review explored the role of metaphor specifically within the police context. Researchers Paul Thibodeau, Latoya Crow, and Stephen Flusberg asked several questions about the role of competing metaphors—namely, “guardian” vs. “warrior”—in the perceptions of police.

The first question addressed how different valences of the metaphors might emerge in the specific policing context: Intriguingly, the terms “guardian” and “warrior” express similar positive valence in a neutral context (i.e., when people presumably do not think about the police at all). So what would happen if people are primed to think about the police when considering the meaning of the two words?

In their first study, Thibodeau and colleagues asked their participants (MTurk workers) two free response questions: “What are some qualities of a warrior?” and “What are some qualities of a guardian?” In one condition, participants performed the task without any further context. In another condition, people were first asked about their attitudes towards policing, using items such as “How would you describe the criminal justice system in the US?” (with response options from “Very far from the ideal” to “Very near to the ideal”). Participants in that condition were also asked which of the two metaphors—”guardian” vs. “warrior”—better described the police.

The figure below shows the data, expressed as the valence of people’s associations to the two metaphors—with positive and negative attributes represented in the two different panels. “Warrior” carried more negative valence overall than “guardian”, and when that term is used in the police context, it seems to draw out an especially negative connotation. By contrast, “Guardian” has a more positive connotation in the police context than “warrior.”

People were almost evenly split on which metaphor was more apt to describe the police, but their choice was highly predictive of attitudes towards the police: People who thought of police officers as “guardians” of the community had a far more positive view of policing than people who thought of the police as “warriors.”

However, the data from the first study were entirely correlational: that is, people reported their own choice of metaphor and their attitudes towards policing, and it is therefore unclear whether the choice of metaphor determines attitudes, or vice versa (or whether both are manifestations of the same underlying attitude).

The second and third study of Thibodeau and colleagues therefore manipulated the metaphor explicitly. In one condition, participants read that “Police officers are the guardians of modern communities—strong men and women who serve a vital role in society, often placing themselves in harm’s way in order to protect their fellow citizens”. In another condition, the explanation was “Police officers are the warriors of modern communities—strong men and women who serve a vital role in society, often placing themselves in harm’s way in order to fight for their fellow citizens”.

This fairly subtle manipulation had a notable effect on people’s attitudes: In both studies, participants who were presented with a metaphor of police officers as guardians of the community reported a more positive attitude toward policing than participants who received the warrior metaphor.

By what mechanism did presentation of the metaphor shape people’s attitudes towards policing? Thibodeau and colleagues sought to explore this issue by breaking down their overall attitude scale into the different item types, and examining the impact of the metaphor manipulation on the different item types separately. The figure below shows the effect sizes of the manipulation for all studies broken down by item.

We can ignore the light bars from the first, correlational study because the direction of causality for those data is unclear. When we consider the dark bars, it is apparent that the effect of the manipulation was stronger for items that related to the system of policing and administering justice (two bottom bars) than for items that queried aspects of a police officer’s job, such as how difficult it is (top two bars).

Given that the U.S. clocked up as many fatal police shootings in the first 24 days of 2015 as England and Wales did in the last 24 years, it appears advisable that we carefully consider the choice of metaphors in our conversation about policing. The research by Thibodeau and colleagues thus provides empirical support for the linguistic strategy proposed by the Obama task force.